Change the default createdump memory enumeration to the fast path (#81922)

Change the default createdump memory enumeration to the fast path (#81922)

* Change the default createdump memory enumeration to the fast path

Also reduces the memory createdump uses generating a dump.

Setting DOTNET_EnableFastHeapDumps=0 opts out going back to the
slow/high memory usage generation.

Issue: https://github.com/dotnet/runtime/issues/72148

* Update src/coreclr/debug/createdump/crashinfo.cpp

Co-authored-by: Noah Falk <noahfalk@users.noreply.github.com>
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Co-authored-by: Noah Falk <noahfalk@users.noreply.github.com>